Tamping punch stations are used in capsule filling machines, which may be designed as so-called rotary machines. They have different process stations distributed around the perimeter, in particular a feeding station and separating station for separating the capsule halves, one or more dosing stations, a closing station for closing the capsule halves, one or more ejection stations and, if applicable, one or more emptying stations. Tamping punch stations for example are used as dosing stations, which are suitable for dosing filling material and transferring it to capsules.
The diameter and distance between the bore holes of tamping punch stations are adjusted for the capsules to be filled that are held in a capsule holder of the capsule filling machine. The tamping punch station includes for example five groups of tamping punches and one group of ejection punches. At the groups of tamping punches, pellets are gradually created in the bore holes from the filling material. The group of ejection punches pushes the pellets out of the bore holes and transfers the pellets thusly into the bottom parts of the capsules held in the capsule holders.
A dosing disk is often driven incrementally via a step switching gearbox so that the individual groups of bore holes approach successively the groups of tamping punches and the group of ejection punches. Each cycle is divided into a rest time and a switch time. The rest time is the standstill time, in which the dosing disk sits and the pellets are formed or respectively ejected. The switch time is the movement time of the dosing disk, in which the dosing disk rotates around its axis and each group of bore holes cycles further to the next group of punches. The ratio between switch and rest time is determined during the course of the design of the step switching gearbox and cannot be changed after that.
Moreover, tamping punch stations have a lifting device, which carries the tamping punches and the ejection punches and moves, e.g. up and down vertically, according to the clocked movement of the dosing disk. The lifting device is generally driven by a mechanical cam, wherein the stroke length is determined one time during the design of the tamping punch station and is also no longer adjustable. The pellets are built in stages through different fastening heights of the groups of tamping punches on the lifting device. In order to ensure that the rotation of the dosing disk and the movement of the lifting device are synchronized, both drive trains are mechanically coupled and driven by a common drive. While the dosing disk is in its switch time and rotates for example at six groups of bore holes by 60°, the tamping punches already begin their vertical downwards movement. They reach the bore holes of the dosing disk and, if applicable, a powder bed made of filling material only when the dosing disk has already reached its position for the rest time. After the pressing procedure, the punches move back into their initial position, wherein the dosing disk already begins to turn further before the punches have reached their uppermost position.
A further tamping punch station is known from DE 10 2006 014 496 A1. The punches are thereby held on a support, which is driven via columns. The columns are connected with a common servodrive via a crank drive so that the columns should run synchronously.